1. Field of the Invention
The present invention relates to a matrix powder system, a composite material including the matrix powder system, and a matrix bit body made of such a composite material for a drill bit used for oil and gas drilling. More specifically, the present invention relates to a matrix powder system that includes one or more polycrystalline carbides, binderless carbides, or a combination thereof, said polycrystalline and/or binderless carbides comprising carbides of W, Ti, V, Cr, Nb, Mo, Ta, Hf, Zr, or a combination thereof.
2. Description of Related Art
An earth-boring drill bit 1 used for oil and gas drilling, as shown in FIG. 1, includes several cutting elements 2 which are attached to a drill bit body 4. Drill bits of this type may also be referred to as shear bits, shear matrix body cutters, or matrix body drill bits. The drill bit body 4 is made of a composite having a hard matrix phase that contains one or more ceramic components, such as cast tungsten carbide, macrocrystalline tungsten carbide, agglomerate carburized tungsten carbide, crushed cemented tungsten carbide, tungsten carbide-cobalt/nickel pellets, and/or other carbides, nitrides, borides, and/or oxides in the form of small particles.
The cutting elements 2 are most commonly discrete diamond or polycrystalline diamond composites on a cemented carbide substrate attached to the drill bit body 4 by brazing or by a mechanical/metallurgical bond with the drill bit body material.
Commonly, the matrix material drill bit body is manufactured using an infiltration process which bonds the small matrix particles using a metal bond phase. In the infiltration process, a matrix powder is poured into a mold. The infiltration metal, which will become the metal bond phase of the composite, is then placed on top of the matrix powder. After the mold is loaded, a top is positioned over the mold and the mold is heated in a furnace to a temperature above the melting point of the metal bond phase but below the melting point of the ceramic components of the matrix powder. The metal bond phase melts and infiltrates the matrix powder. After cooling and solidification, the metal bond phase bonds the matrix powder together to form a solid composite. A steel shank is either bonded to the drill bit body 4 after solidification or placed in the mold prior to heating, such that the infiltrate metal bonds the shank to the drill bit body 4. The cutters 2 are attached to the drill bit body 4 after solidification using brazing or another suitable attachment method to secure them in grooves or recesses formed in the drill bit body 4 by the mold.
U.S. Pat. No. 7,475,743 to Liang et al. describes an earth-boring drill bit having a matrix bit body containing cemented tungsten carbide and cast tungsten carbide manufactured using the infiltration method. In the Liang patent, the cutting elements are brazed to the matrix bit body after it has been manufactured using the infiltration method. United States Patent Application Publication No. 2008/0206585 to Deng et al. describes a drill bit having a matrix bit body containing carbides, borides, nitrides, and/or oxides manufactured using the infiltration method.
During the infiltration process used to manufacture the matrix material drill bit body, temperatures reach about 1200° C. It is, therefore, necessary for the matrix components, i.e., the carbides, to have good thermal stability so that they do not break down during the manufacturing process.
During operation, such earth-boring drill bit bodies are subjected to a significant amount of erosion and impact. Although the cutters 2, which are made of diamond or polycrystalline diamond composites, have high hardness and good erosion resistance in service, the currently used drill bit bodies 4 are less erosion resistant. As a result, the limiting factor for the life of the drill bit is the degradation of the drill bit body 4.
Therefore, a composite material is needed for the drill bit body 4 that contains a matrix powder system having better thermal stability to tolerate the manufacturing process and higher hardness and better erosion resistance to more closely match the hardness and erosion resistance of the cutters 2.